Question about composits ( non car related)

[innerware]

So, don't know if any of you remember the composit travel guitar I built a while back. Well, my partner and I have redesigned it and are going ahead with another build. I would like to do this one the proper way with a negative mold (female) gell coat first then layers of matte glass.

 

1st question. How do you accurately trim a part from a mold before removing it? I would need the part to be perfectly trimmed to withing .003 of an inch if at all possible. It is a one piece back, neck, sides design and if it is in accurate then the guitar won't set up correctly.

 

2nd question. Is there someone that you all recoment in the Bay Area that is this good that I can purchase layup skills from. We are not at all against farming it out.

 

3rd question. Do you all recomend any good reading material that shows proper mold design for this type of application? I do know a bit of what I am doing but I now need it to be professionally done and would like to have all the knowledge I can gather.

 

I am building the positive for the new guitar soon and it will be all done professionally with a nice layer of release wax. This I have done before and it doesn't concern me. Just the proper mold design. The mold will be a one piece mold as the sides have enough draft angle to release and allow the part to be pulled.

 

Thanks for all the help. I will post pics later of the new design. It is all drawn in solidworks and rendered nicely. But since we are going to hopefully take this one to production after the new prototype is made I probably can't show it around untill the trade shows next Jan. This model will be used for us to find capital so it can be manufactured elsewhere. That's the plan anyway.

 

Thanks again

[RedFive]

If you want it done professionally, I would suggest sending it out to a stereolithography shop. Most of those places can make you a plastic or plaster mold very quickly and it'll basically be perfect. I am currently in the process of molding something for the Z with my school's machines.

[innerware]

Thanks. Have thought of that. But it will be quite expensive and would have to be done in multiple stages. It is a guitar after all. I guess I am just looking for a person who could make the part for me after I make the mold.Or make the mold and part for me after I make the plug. I know from experience having parts SLA'd or FDM'd that this particular part would cost over a grand to have printed.

 

Any books you all like on fiberglass mold building?

[RedFive]

Yeah, I know it'll be expensive. But if you're going to be selling it then supposedly you'll make the money back.

 

Is the neck made out of fiberglass too? I would worry about axial stress and shear stress and stuff if you made it all out of fiberglass. You might think about some sort of composite. But then again, you could probably do it in fiberglass if you make sure you have the correct type of geometry to resist the load you're going to apply.

 

But hell, it's just a guitar. I guess if it bends too much you'll just have to retune it more often!

[DaleMX]

Sound's like an awesome idea. I do vacuum lamination on fiberglass circuit boards and my bag supplier (Airtech) may have the supplies and details necessary for you to perform this feat. PM me with your email address and I'll put you in touch.

 

I assume that you would build a small amout of reverse taper into the neck and maybe incorporate a small hollow tube toward the rear to run an adjustable steel rod into for fine tunning the neck taper.

[zguy36]

What are you trying to achieve with a composite guitar? Is this just for a cool factor, or for lightness? If you want lightness, then wood would be your best bet, instead of a hollow glass one. Post your solid model of your idea in the downloads section so we can take a look. Don't use carbon fiber, as it has good vibration damping capabilities. That wouldn't be good for an instrument that is supposed to be vibrating!

[innerware]

Here is the picture of the existing "old design" http://album.hybridz.org/showgallery.php?cat=617

It has a hollow neck and the back is made out of a fiberglass twill and the top carbon fiber. It is done this way to save weight, be strong and moisture resistant, and travel friendly. It actually does sound good too. We have redesigned it and made it look better and solved some issues we had with the first prototype.

 

My questions are now about making another one but better. I was able to make the first but just winged it since I had no composit experience previous. This next one I would like to do it as professionaly as possible. So, that said,

 

here are the same questions:

1st question. How do you accurately trim a part from a mold before removing it? I would need the part to be perfectly trimmed to withing .003 of an inch if at all possible. It is a one piece back, neck, sides design and if it is in accurate then the guitar won't set up correctly.

 

2nd question. Is there someone that you all recomend in the Bay Area that is this good that I can purchase layup skills from. We are not at all against farming it out.

 

3rd question. Do you all recomend any good reading material that shows proper mold design for this type of application? I do know a bit of what I am doing but I now need it to be professionally done and would like to have all the knowledge I can gather.

 

Thanks guys.

[DaleMX]

I dont see the need for such accuracy. Seems the me that after you get it roughed out you would mill in the fret slots and bridge location. Anyway a rosewood inlay would be a nice touch.

 

Ever been here? > http://www.mimf.com/

[innerware]

The inlays for the frets and bridge aren't the problem. It is the fact that the sides, neck, and back are all one piece. The soundboard is also one piece that extends up all the way to the head. The fret board and bridge are attached after. The accuracy is important so the neck remains straight with the proper negative neck relief built into it. Also the bridge has to be level in relationship to the fret board. So essentially the intire surface has to be level and flat with a minute amount of negative bow in the neck. We aren't using a truss rod and will set it up so it won't need adjusting. The first one we made so far hasn't bent or come out of true. But I want this one to be made better.

 

And rosewood is a nice touch. Used it on the first one. I think it adds a warm touch to it.

 

Thanks again for any advice and links to info.